Update the node version from 0.8.23 to 0.8.26

Given the recent security advisory about versions < 0.8.26 regarding HTTP server memory exhaustion and the likelihood that people will have public facing Hipache instances we should bump the version. Safety first!
Merge pull request #52 from patrickod/patch-1

Update the Dockerfile node version from 0.8.23 to 0.8.26